This has been doing my head in for a few days. SOLIDWORKS is lacking a method for finding the rotational direction (counter or clockwise) for a circular ICurve. There seem to be a method for the ISketchArc but not for the curve.
The ICircleParams gives the axis vector which I think can be utilized to finding the rotational direction SOLIDWORKS used to draw the arc. Obviously, this will depend if you're viewing the arc from below or above but this shouldn't be an issue. I tried to dot ARC axis and the Face's normal to see if they are pointing in the same sense and considered it counter-clockwise. Did a game of trial but the results are still incorrect, there seem to be something lack.
If anyone finds a solution to this, let's put it out here for future people to use this as I think this would be very useful.